/**
 * ticker.ts, something has to run the sweep.
 *
 * A loop that only runs when a verb asks it to is not proactive, and proactive
 * is the whole feature. This is the repeating timer that runs it, with the
 * timer itself injected so its behaviour is testable by advancing a counter
 * rather than by waiting an hour.
 *
 * The ticker is deliberately DUMB, because the sweep is where the judgement is:
 *
 *  - A tick inside quiet hours raises nothing and reaps anyway.
 *  - A tick on a day an occasion has already been raised finds its open item
 *    not yet due and raises nothing.
 *
 * So the interval decides how soon the FIRST nudge lands after a window opens,
 * and nothing else. Shortening it cannot make the system nag.
 *
 * Three properties that are easy to get wrong in a self-rearming timer, all
 * asserted by test:
 *
 *  - **The interval is re-read every tick**, so `occasions.sweepIntervalMinutes`
 *    is a live setting rather than a restart-only one.
 *  - **Passes are strictly serial.** The next tick is armed only once the
 *    current pass has finished, so a slow sweep, delivering over a channel,
 *    say, delays the next pass rather than having one start on top of it. Two
 *    overlapping passes would deliver the same batch twice, and the fix for
 *    that is not to have a second one to skip.
 *  - **A failing sweep re-arms.** One transient error must not stop the loop for
 *    the life of the process, which is what a naive `await` inside the timer
 *    body does.
 */
/** The timer surface this needs, injected so a test can drive it. */
export interface TickerScheduler {
    setTimeout(handler: () => void, ms: number): unknown;
    clearTimeout(handle: unknown): void;
}
export interface SweepTickerOptions {
    /** One pass. Its own errors are caught here; it never has to be safe. */
    readonly sweep: () => Promise<unknown>;
    /** Read fresh on every tick, so the setting is live. Milliseconds. */
    readonly intervalMs: () => number;
    readonly scheduler?: TickerScheduler | undefined;
    /** Called when a pass throws, so the failure is on the record. */
    readonly onError?: ((error: unknown) => void) | undefined;
}
export interface SweepTicker {
    /** Stop the loop. Safe to call more than once. */
    stop(): void;
    /** True while a pass is in flight. Test seam. */
    readonly running: boolean;
}
export declare function startOccasionSweepTicker(options: SweepTickerOptions): SweepTicker;
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